Client side

I was wondering if any 1 knows how to make a client side map and a server side map like hunts did so other servers can not steal your map you are using,
so basically when the players download the map there are no entities at all but then when they join your server are the entities are on but its not a different map that they have to download.

Kinda hard to explain but i was wondering how they did that.

Would probably have to be coded with lua.

Maybe you can find the developers and ask them in person?